摘要
在高温高压条件下,金属触媒与石墨形成的碳化物Me3C(Me为Fe、Ni)是形成金刚石结构的主要碳源。利用固体与分子经验电子理论(EET),计算了多种Me3C型碳化物和金刚石的价电子结构以及表征界面性质的电子结构参数,并将程氏理论(TFDC)提出的原子界面边界条件应用到碳化物/金刚石界面,发现碳化物晶胞中C—C键络组成的晶面与金刚石中的某些晶面的电子密度在一级近似下是连续的,但不同碳化物其连续程度不同,其中Co3C和(FeNi)3C中碳原子组成晶面的价电子结构与金刚石中的最接近,其C—C键转化为金刚石结构需要的能量最低。从电子结构角度上解释了催化机制及不同触媒的催化效果,价电子理论是探讨金刚石催化机制的新途径。
Experimental results showed that the Me3C（Me means Fe,Ni） pattern carbides produced by the action of catalyst and graphite are main carbon source to form diamond structure under high temperature and high pressure（HPHT）. In this paper,based on the empirical electron theory of solids and molecules（EET） ,the valence electron structure（VES） and interface structure factors of diamond and various carbides are calculated, and the boundary condition of Thomas-Fermi-Dirac-Cheng（TFDC） is applied to the carbide/diamond interfaces. It is found that the electron density of crystal face in Me3C formed by C-C bonds is continuous with that of diamond at the first order of approximation, but the continuous intensity of different carbide is different. The VES of plane composed of C atoms in（FeNi）3 C and Co3C are more similar to that of diamond,so the energy needed to transform their C-C bonds to diamond structure is lower. The catalyst action and catalysis mechanism are explained on the basis of VES concerning the carbides and diamond. This method may be a new way to investigate the mechanism concerning diamond formation.
出处
《高压物理学报》
EI
CAS
CSCD
北大核心
2006年第4期372-378,共7页
Chinese Journal of High Pressure Physics
基金
国家自然科学基金(50371048
50372035)
关键词
金刚石单晶
碳化物
高温高压
价电子结构
界面
触媒
diamond single crystal
carbide
HPHT
valence electron structure
interface
catalyst
